Re: Whacked out computer?

Tim,
The newer 1284 parallel specs are a somewhat wimpy for driving opto-
couplers fast. Especially the The DC steady state specs below. Maybe
the-all-in-one port chip is not robust. Be interesing if you put a
'hc541,'hc244' or 'hc245 inline and see what it does. I wonder if it
really is getting set into the legacy mode by the bios. The software
probably doesnt know all the details to check it.
Sounds like you got it solved anyway. :-)
p.s. I have to throw in my 2cents every now and then or
else they'll de-list me ;-)
-Lee


From http://www.fapo.com/1284elec.htm:

"The 1284 standard defines two levels of interface compatibility, The
requirements for the Level II drivers and receivers are defined at
the connector interface. The driver requirements are:

The open circuit high-level output voltage shall not exceed +5.5V.
The open circuit low-level output voltage shall be no less than -
0.5V.
The DC steady state, high-level output voltage shall be at least
+2.4V at a source current of 14mA.
The DC steady state, low-level output voltage shall not exceed +0.4V
at a sink current of 14mA.
The driver output impedance (Ro), measured at the connector, shall be
50 +/- 5 ohms at 1/2 the actual driver Voh minus Vol voltage.
The driver slew rate shall be 0.05-0.40 V/nS
Like the driver requirements, the receiver requirements are defined
at the connector interface. The receiver requirements are:

The receiver shall withstand peak input voltage transients between -
2.0V and +7.0V without damage or improper operation.
The receiver high-level input threshold shall not exceed 2.0V
The receiver low-level input threshold shall be at least 0.8V.
The receiver shall provide at least 0.2V input hysteresis, but not
more than 1.2V.
The receiver high-level sink current shall not exceed 20uA at +2.0V.
The receiver low-level input source current shall not exceed 20uA at
+0.8V.
Circuit and stray capacitance shall not exceed 50pF.

--- In CAD_CAM_EDM_DRO@y..., "Tim Goldstein" <timg@k...> wrote:
> Lee,
>
> Yes I am using a direct +5v from a drive connector.
>
> I just got it to work. Dan's suggestion that the port was the
problem
> prompted me to open the box and drop in an ISA parallel port card I
had
> on hand. Set it for 378 IRQ7 and disabled the onboard port in bios.
> Booted it up and with the parallel cable plugged into the new port
it
> works perfect. No other changes required.
>
> Tim
> [Denver, CO]
> Sherline products at Deep Discount
> www.KTMarketing.com/Sherline
>
>
> > -----Original Message-----
> >
> > Hi Tim,
> > Have you run a separate ground wire( or +5v line) for the optos
from
> > the PC. At first glance it sounds like some an uncommon reference
> > problem. Put a scope on the lines to check the levels and for
ringing
> > also.
> > -Lee
> >
> >
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